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Patented Apr. 8, 1924.

UNITED STATES PATENT OFFICE.

RAYMOND DAY wnnnnna AND oerAvn DEGRENIER, or sournearnen, MASSACHU- sn'rrs, .assienons r0 AMERICAN OPTICAL COMPANY, or sou'rnsnmen, MASSA- onusnrrs, A VOLUNTARY ASSOCIATION or MASSACHUSETTS.

LENS-MARKING DEVICE.

No Drawing.

To all whom'it may concern:

Be it known that we, RAYMOND VVHEELER and OGTAVE DEGRENIER, of the United States, residing at S bridge, in the county of Worcester DAY citizens outliand State of Massachusetts, have invented certain new and useful Improvements in Lens- Marking Devices, of which the following is a specification.

This invention relates to new and useful improvements in. ophthalmic lenses and more particularly to a novel and improved commercial lens and to the process of ducing the said article.

pro-

At the present day it is somewhat difficult to distinguish the various types and g rades of lenses placed upon the market by the various manufacturing concerns and the main object of our invention is to produce a new and improved method for marking lenses whereby to distinguish the various g and types by rades the use of characters, letters and the like which are adapted to be marked upon the polished surface of the lens and invisible but which are normally remain rendered visible thru the application of moisture applied to the surface of the lens.

A further object of the invention is the provlsion of a method wherein a lens is produced having portions of its surface mechanically portions of the surface will be provided different hydroscopic properties.

\Vith the above and other objects in modified whereby the different with view

the invention consists in the novel features of construction,

rangement of parts hereinafter more the combination and arfully set forth in the following specification and it is to be understood that we may make any modifications in the structure or steps hereinafter described within the scope of the appended claims without departing from or exceeding the spirit of our invention.

In the carrying out of our invention we first construct a lens from ordinary c or flint glass or a suitable combination of both, surface it in the usual manner on either one or both faces, as preferred. After the lens has been finally finished on at least one surface it is in condition for the carryin out of our process, which consists in app ying to the finished surface of the lens suitable markings in the for mof Application filed August 2, 1922. Serial No. 579,287.

characters, like, thru suitable mechanical mechanism.

The words, characters, symbols, etc., are applied to the finished surface of the lens by means of a diamond having a: ball point which is passed over the polished surface of the lens under pressure so that the ball point of the diamond will tend to crowd down the molecules of the top surface and cause a molecular change in the polished surface of the glass, thus mechanically modifying the hydroscopic properties of the lens, whereby the modified parts will resent a different appearance from the a jacent surface when moistened by the breath.

This surface modification does not destroy any of the polish of the surface of the glass and is invisible under ordinary cir cumstances but is one which will affect the physical condition of the surface in such a manner that upon subjecting the same to slight moisture such as the moisture f the breath when blowing upon the glass, the difference in hydroscopic properties of the surfaces will cause the moisture, as is usual, to condense in globules, but the condensated globules on the modified part will be different as to size. from those on the remainder of the lens, with the result that light striking the surface will be differently affected so that the letters, characters, or symbols will clearly stand out as distinct from the remainder of the lens and may be readily preserved so long as the surface moisture endures but will entirely disappear after the lens surface dries ofi'.

The application of our improved marking is applied with a ball pointed diamond, as heretofore set forth, and is preferably applied underv pressure with the diamond holder normal to the surface being marked so as to force the rounded end or ball point of the diamond on the surface of the glass and eliminate possible scratching by side contact. Various ways and means may be provided for guiding the diamond over the lens, or it may be rotated to accentuate the letters, words, symbols, or the burnishing action of the pressure of the ball surface by crowding down the molecules of the top surface, with a substance harder than the glass surface, whereby a molecular change is produced.

2. The art of invisibly marking glass surfaces consisting in moving a diamond over the surface under pressure, whereby a molecular change is produced.

3. The art of invisibly marking polished glass surfaces consisting in modifying the hydroscopic properties of the surface by moving a blunt point instrument over the surface under pressure, thereby crowding down the molecules of the top surface so that a molecular change is produced in the said surface.

4. The art of invisibly marking polished 

